Passing to the origin of the book, and its author, one can hardly give an account of either only by consulting the book itself in which but little is found except for the base of conjecture. There is only a letter at the beginning, and which is written in another character from the rest of the book, which gives any light. We find it addressed OTHONI, Illustrissimo. The place where the manuscript was found, and the name OTHO put together warrants the belief that it was addressed to the Illustrious Otho, lord of Bavaria. This prince was grandson of Otho, the Great; Count of Schiren and Witelspach from whom the House of Bavaria and the Palatine had their origin. The Emperor Frederick Barbarossa [15] had given him Bavaria for his fidelity, after having taken it from Henry the Lion to punish him for his inconsistency in taking the part of his enemies. Louis I. succeeded his father, Otho the Great, and left Bavaria--in the possession of which he had been disturbed by Henry the Lion--to his son Otho, surnamed the Illustrious, who assured his possession by wedding the daughter of Henry. This happened about the year 1230, when Frederick II., Emperor of Germany, returned from Jerusalem, where, at the solicitation of Pope Gregory IX., he had pursued the war against the Saracens, and from whence he returned irritated to excess against the Holy Father who had incensed his army against him, as well as the Templars and the Patriarch of Jerusalem, until the Emperor refused to obey the Pope. Otho the Illustrious recognizing the obligations that his family were under to the family of the Emperor, took his part and remained firmly attached to him, notwithstanding all the vicissitudes of fortune of Frederick. Why these historical reminiscences? To sustain the conjecture that it was to this Otho the Illustrious that this copy of the pamphlet of the Three Impostors was addressed. By whom? This is why we are led to believe that the F. I. s. d. which follows L'amico meo carissimo, and which we interpret FREDERICUS. Imperator salutem Domino. Thus this would be by The Emperor Frederick II., son of Henry IV. and grandson of Frederick Barbarossa, who, succeeding to their Empire, had at the same time inherited the hatred of the Roman Pontiffs. [16]